Teams are trying to figure out what happened at the International Polo Club Palm Beach in Florida.

State and local veterinary teams are trying to figure out what happened at the International Polo Club Palm Beach in Wellington, Florida, as team Lechuza Caracas prepared to compete in a U.S. Open match.

Two horses initially collapsed, and as vets and team officials scrambled to revive them, five others became dizzy, said Tim O'Connor, spokesman for the polo club.

"A total of seven died on our property," O'Connor told CNN. Seven other horses died en route to a Wellington horse farm and a veterinary hospital.

The cause of the deaths has not been determined, and necropsies and blood tests were underway, he said.

O'Connor said each team brings between 40 to 60 horses for matches, and they are continuously switched out throughout a match to keep the horses from overexerting themselves.

A meeting will be held to determine whether Lechuza Caracas will compete at a later date, he said.

"Everybody is kind of in shock and trying to figure out what happened," he said. "Nobody can recall an incident in which this many horses have died at once."

"Remember - every time your dog gets somewhere on a tight leash *a fairy dies and it's all your fault.* Think of the fairies." http://www.positivepetzine.com"

Jeebus. What can kill that many horses so quickly? I can't imagine it's a natural illness. I know Swamp Fever (can't remember the technical name of it) is super-contagious but I don't think it kills that quickly. Very scary.

"Remember - every time your dog gets somewhere on a tight leash *a fairy dies and it's all your fault.* Think of the fairies." http://www.positivepetzine.com"

Nah, Swamp fever is Equine infectious anemia, and it would be very very weird that it went unnoticed in polo/any show horses, which MUST get a Coggin's to go from barn to barn... So if they were positive they'd be quarantined forever in a screened barn or euthanized right away.

This is sooo weird, them dropping dead like this. I don't know if something in the environment was different (those horss are pretty tough, especially concerning heat, they're used to it)... Feed? Grass? New disease?

(CNN) -- Florida agriculture scientists are performing necropsies Monday on 21 horses that died as they were prepared to compete in a Sunday polo match in Wellington, Florida.

Teams are trying to figure out what happened at the International Polo Club Palm Beach in Florida.

"We'll be testing blood and tissue to see what the common denominator was here -- was it something injected, was it bad water and so forth," said Terrence McElroy, a spokesperson for the Florida Department of Agriculture and Consumer Affairs.

The horses were part of the Venezuelan-based Lechuza Caracas team and were being kept at the team's trailers on the grounds of the International Polo Club. Fifteen horses, that seemed disoriented, died before Sunday's match, said McElroy, and their bodies were sent to the state-run Kissimmee Diagnostic clinic near Orlando.

Two horses initially collapsed, and as vets and team officials scrambled to revive them, five others became dizzy, Tim O'Connor, spokesman for the polo club, told CNN on Sunday. As vets and team officials scrambled to revive them by running intravenous tubes into the horses, five others became dizzy.

Some of those horses died immediately, but some lingered for about 45 minutes, Dr. Scott Swerdlin of the Palm Beach Equine Clinic said, according to a report in the Sun-Sentinel newspaper. The clinic is the International Polo's consulting veterinarian group, the newspaper said.

Six out of the 21 horses were kept overnight in the same trailer in Wellington, said McElroy, and died overnight there. Their bodies had not been taken to the Kissimmee lab.

The U.S. Polo Association, the sport's governing body, is expected to open an investigation Monday.

Celeste Kunz, chief examining veterinarian at the New York Racing Association and 19-year veterinarian said Monday that she suspected a tainted substance was injected into the horses.

"[It was] something that was administered for it to work in a short amount of time and have an animal succumb that quickly," she said. "My thought is that something was injected because it would have to affect the central nervous system."

She dismissed the chances that the horses ingested something because it would take longer to metabolize and they would show signs of illness sooner than they did before the match.

Anabolic steroids are not the likely to have caused the deaths either, she explained.

"It takes at least 5 days for [anabolic steroids] to really work and the affects aren't real obvious at first," she said. "Most of the time [anabolic steroids] are used to build up their muscularity."

Each team brings between 40 to 60 horses for matches. The ponies are continuously switched out throughout a match to keep them from overexerting themselves, he said.

The horses were between 10 and 11 years old, and were valued at about $100,000 each, O'Connor said, according to the Sun-Sentinel.

A meeting will be held to determine whether Lechuza Caracas will compete at a later date, he said.

"Everybody is kind of in shock and trying to figure out what happened," he said. "Nobody can recall an incident in which this many horses have died at once.

"Remember - every time your dog gets somewhere on a tight leash *a fairy dies and it's all your fault.* Think of the fairies." http://www.positivepetzine.com"